Astronomy Free: eclipses, planets and constellations
Install the appFree, no sign-up, works in your browser. See every eclipse, meteor shower and planet event of the coming year, the planets today, all 88 constellations and over 500 deep-sky objects. Worked out on your device for where you are.
Privacy at a glance
All details- Offline: Fully
- Your data: On device
- Sync: When signed in
- Processing: On device
- AI: None
- Camera & mic: None
- Ads & tracking: Not in app
Ads & tracking: none in the installed app. This page uses analytics and may show ads.
Astronomy
Free · works offline · reminders on your phone
Why use Astronomy
- Worked out on your device
- Events and positions are computed on your phone, so it all works offline once installed.
- Eclipse dates that are checked
- Every eclipse from 2021 to 2030 is tested against Fred Espenak's published tables.
- Your data is yours
- Saved events and sightings stay on your device, or sync if you sign in, and you can download or delete them at any time.
- 100% free
- Use it as often as you like. No sign-up and no watermark.
- Private by design
- Your location is used on this device to work out what you can see, and stays there. Events you save and things you mark as seen stay on this device, or sync to your account if you sign in, and you can download or delete them at any time.
- Works on any device
- Runs in your browser on Windows, Mac, Linux, Android and iPhone, or install it on your phone to use it offline.
Who it's for
- Plan around an eclipse
- See the coming year's eclipses, and with your place set, how much of the Sun is covered where you are and at what time.
- Pick a night for meteors
- Each shower's peak comes with how much of the Moon is lit, because a bright Moon drowns out all but the brightest.
- Find out what's up tonight
- See where each planet is today and, with your place set, the best time and direction to look.
- Work through the Messier list
- Look up every object on Messier's list and mark each one as you see it.
How Astronomy compares
| Option | How it compares |
|---|---|
| A printed astronomy calendar | A printed calendar is lovely on a wall, but it can't tell you what you'll see from your own place or remind you the day before. |
| Stars Overhead | Stars Overhead shows the live sky when you point your phone at it. Astronomy is for planning ahead, and links to it. |
How to use Astronomy
- Open the calendar to see the next twelve months of sky events.
- Add your place to find out which eclipses you can watch, and when.
- Save an event and turn on a reminder so you don't miss it.
- Look up a constellation or a deep-sky object, and mark what you've seen.
Install it on your phone
iPhone and iPad (Safari)
- Tap Install the app, or open the app's page in Safari.
- Tap the Share button.
- Choose Add to Home Screen, then tap Add.
Android (Chrome)
- Tap Install the app, or open the app's page in Chrome.
- Tap Install when it asks, or open the ⋮ menu and choose Install app.
- Open it from your home screen.
Windows, Mac and Linux (Chrome or Edge)
- Tap Install the app.
- Click the install icon at the right of the address bar, then Install.
Installing is free, and the app opens like any other app on your phone.
Frequently asked questions
Where do the eclipse dates come from?
They're worked out on your device with the open-source Astronomy Engine. We check every eclipse from 2021 to 2030 against the published tables by Fred Espenak.
Does it use my location?
Only if you ask it to. Your place stays on this device and is used to work out what you can see. You can also type it in, or use the app without one.
Why don't the constellation lines look like the ones I know?
Each figure is the shortest route through the constellation's brightest stars, worked out by the app. It shows which stars are there, not the traditional picture.
Is it safe to watch a solar eclipse?
Only with certified eclipse glasses or a proper solar filter, except during the brief total phase. The app says so on every solar eclipse.
Can I use it offline?
Yes. Once installed, everything works without a connection, because it's all worked out on your device.
Is Astronomy free?
Yes. It's free to use, with no sign-up, and installing it on your phone is free too.
Related tools
- Stars OverheadHold your phone up to the night sky and see the names of the stars and planets in that direction, or drag the sky with a finger on any phone or computer. It shows 9,096 stars, the Moon and the planets for where you are, and the words stay on screen if the compass can't be trusted. It works offline and installs like an app.
- What's Up TonightSearch for a city, use your location or type coordinates to see when it gets dark and which planets you can see tonight, where to look and how bright they are, plus moonrise and moonset. It runs on your device, with no account.
- Moon Phase CalculatorPick any date from 1600 to 2400 to see the Moon's phase, how much of it is lit and its age, with every new moon, quarter and full moon of that month. It runs on your device, with no account.